U.S. patent application number 11/569361 was filed with the patent office on 2007-10-18 for amine compound and organic electroluminescent element employing the same.
This patent application is currently assigned to Idemitsu Kosan Co., Ltd.. Invention is credited to Toshikazu Hirao, Chishio Hosokawa, Hirofumi Kondo, Masami Watanabe.
Application Number | 20070243416 11/569361 |
Document ID | / |
Family ID | 35450815 |
Filed Date | 2007-10-18 |
United States Patent
Application |
20070243416 |
Kind Code |
A1 |
Watanabe; Masami ; et
al. |
October 18, 2007 |
Amine Compound and Organic Electroluminescent Element Employing the
Same
Abstract
An amine-based compound having a specific structure and an
organic electroluminescence device which comprises at least one
layer comprising at least a light emitting layer and is disposed
between a cathode and an anode, wherein at least one layer in the
organic thin film layer comprises the amine-based compound singly
or as a component of a mixture. The organic electroluminescence
device exhibits an excellent balance in physical properties such as
a small ionization potential, a great band gap energy, a great
efficiency of injection and a great mobility and excellent heat
resistance and current efficiency due to the amine-based
compound.
Inventors: |
Watanabe; Masami; (Chiba,
JP) ; Hosokawa; Chishio; (Chiba, JP) ; Kondo;
Hirofumi; (Chiba, JP) ; Hirao; Toshikazu;
(Hyogo, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Idemitsu Kosan Co., Ltd.
1-1, Marunouchi 3-chome Chiyoda-ku
Tokyo
JP
100-8321
|
Family ID: |
35450815 |
Appl. No.: |
11/569361 |
Filed: |
May 27, 2005 |
PCT Filed: |
May 27, 2005 |
PCT NO: |
PCT/JP05/09754 |
371 Date: |
November 20, 2006 |
Current U.S.
Class: |
428/704 ;
428/411.1; 540/1; 544/353; 544/356; 548/126; 548/257; 564/434 |
Current CPC
Class: |
C09K 2211/1044 20130101;
C09K 11/06 20130101; C09K 2211/1014 20130101; H05B 33/14 20130101;
Y10T 428/31504 20150401; C07D 241/42 20130101 |
Class at
Publication: |
428/704 ;
428/411.1; 540/001; 544/353; 544/356; 548/126; 548/257;
564/434 |
International
Class: |
C07D 241/38 20060101
C07D241/38; C07D 249/18 20060101 C07D249/18; C07D 271/12 20060101
C07D271/12; C07D 285/14 20060101 C07D285/14; C09K 11/06 20060101
C09K011/06; H05B 33/14 20060101 H05B033/14; H05B 33/22 20060101
H05B033/22 |
Foreign Application Data
Date |
Code |
Application Number |
May 28, 2004 |
JP |
2004-158560 |
Claims
1. An amine-based compound represented by general formula (1) or
(2): ##STR42## wherein X represents a substituted or unsubstituted
arylene group having 4 to 50 carbon atoms or a group represented by
following general formula (3) or (4), a plurality of X may
represent a same group or different groups, and at least one of the
plurality of X in general formulae (1) and (2) represents a group
represented by one of general formulae (3) and (4); Y represents a
substituted or unsubstituted aryl group having 4 to 50 carbon atoms
or a substituted or unsubstituted heterocyclic group having 5 to 50
carbon atoms, and a plurality of Y may represent a same group or
different groups; n presents an integer of 0 to 3; and each N
represents a nitrogen atom; general formulae (3) and (4) being:
##STR43## wherein R.sup.1 and R.sup.2 each independently represent
hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl
group having 1 to 50 carbon atoms, a substituted or unsubstituted
alkoxyl group having 1 to 50 carbon atoms, a substituted or
unsubstituted aryloxyl group having 4 to 50 carbon atoms, a
substituted or unsubstituted thioalkoxyl group having 1 to 50
carbon atoms, a substituted or unsubstituted thioaryloxyl group
having 4 to 50 carbon atoms, a substituted or unsubstituted amino
group, a substituted or unsubstituted aryl group having 4 to 50
carbon atoms, a substituted or unsubstituted alkylcarbonyl group
having 1 to 50 carbon atoms or a substituted or unsubstituted
arylcarbonyl group having 4 to 50 carbon atoms; atoms and groups
represented by R.sup.1 and R.sup.2 may be same with or different
from each other; and adjacent groups represented by R.sup.1 may be
bonded to each other to form a cyclic structure, and adjacent
groups represented by R.sup.2 may be bonded to each other to form a
cyclic structure; and Z represents sulfur atom, oxygen atom or
--NR.sup.3--, R.sup.3 representing hydrogen atom, a substituted or
unsubstituted aryl group having 4 to 50 carbon atoms, a substituted
or unsubstituted heterocyclic group having 5 to 50 carbon atoms or
a substituted or unsubstituted alkyl group having 1 to 50 carbon
atoms.
2. The amine-based compound according to claim 1, wherein n in
general formula (I) represents 1.
3. The amine-based compound according to claim 1, which is a hole
injecting material or a hole transporting material.
4. The amine-based compound according to claim 1, which is a hole
injecting material or a hole transporting material for organic
electroluminescence devices.
5. An organic electroluminescence device which comprises a cathode,
an anode and an organic thin film layer which comprises at least
one layer comprising at least a light emitting layer and is
disposed between the cathode and the anode, wherein at least one
layer in the organic thin film layer comprises the amine-based
compound described in claim 1 singly or as a component of a
mixture.
6. An organic electroluminescence device which comprises a cathode,
an anode and an organic thin film layer which comprises at least
one layer comprising at least a light emitting layer and is
disposed between the cathode and the anode, wherein the organic
thin film layer comprises at least one of a hole injecting layer
and a hole transporting layer, and at least one of the hole
injecting layer and the hole transporting layer comprises the
amine-based compound described in claim 1 singly or as a component
of a mixture.
7. The organic electroluminescence device according to claim 5,
wherein the light emitting layer emits bluish light.
8. The organic electroluminescence device according to claim 5,
wherein the light emitting layer comprises an anthracene derivative
as a host material.
9. The organic electroluminescence device according to claim 7,
wherein the light emitting layer comprises an amine derivative as a
host material or a dopant.
10. An amine-based compound represented by any one of general
formula (1) and (2): ##STR44## wherein X represents a heterocyclic
crosslinking group, and a plurality of X may represent a same group
or different groups; Y represents a substituted or unsubstituted
aryl group having 4 to 50 carbon atoms or a substituted or
unsubstituted heterocyclic group having 5 to 50, and a plurality of
Y may represent a same group or different groups; n represents an
integer of 0 to 3; and each N represents a nitrogen atom.
11. The amine-based compound according to claim 10, wherein n in
general formula (1) represents 1.
12. The amine-based compound according to claim 10, which is a hole
injecting material or a hole transporting material.
13. The amine-based compound according to claim 10, which is a hole
injecting material or a hole transporting material for
electroluminescence devices.
14. An organic electroluminescence device which comprises a
cathode, an anode and an organic thin film layer which comprises at
least one layer comprising at least a light emitting layer and is
disposed between the cathode and the anode, wherein at least one
layer in the organic thin film layer comprises the amine-based
compound described in claim 10 singly or as a component of a
mixture.
15. An organic electroluminescence device which comprises a
cathode, an anode and an organic thin film layer which comprises at
least one layer comprising at least a light emitting layer and is
disposed between the cathode and the anode, wherein the organic
thin film layer comprises at least one of a hole injecting layer
and a hole transporting layer, and at least one of the hole
injecting layer and the hole transporting layer comprises the
amine-based compound described in claim 10 singly or as a component
of a mixture.
16. The organic electroluminescence device according to claim 14,
wherein the light emitting layer emits bluish light.
17. The organic electroluminescence device according to claim 14,
wherein the light emitting layer comprises an anthracene derivative
as a host material.
18. The organic electroluminescence device according to claim 16,
wherein the light emitting layer comprises an amine derivative as a
host material or a dopant.
Description
TECHNICAL FIELD
[0001] The present invention relates to an amine compound
(hereinafter, referred to as an "amine-based compound") and an
organic electroluminescent (hereinafter, "electroluminescent" and
"electroluminescence" will be referred to as "EL") element
(hereinafter, an "EL element" will be referred to as an "EL
device") employing the compound. More particularly, the present
invention relates to an organic EL device exhibiting excellent heat
resistance and efficiency of light emission and an amine-based
compound enabling to obtain the device.
BACKGROUND ART
[0002] An organic EL device is a spontaneous light emitting device
which utilizes the principle that a fluorescent substance emits
light by energy of recombination of holes injected from the anode
and electrons injected from the cathode when an electric field is
applied. The organic EL device exhibits excellent visibility due to
the spontaneous light emission and excellent impact resistance due
to the completely solid structure, and the application to light
emitting elements in various display devices is attracting
attention.
[0003] Since an organic EL device of the laminate type driven under
a low electric voltage was reported by C. W. Tang of Eastman Kodak
Company (C. W. Tang and S. A. Vanslyke, Applied Physics Letters,
Volume 51, Pages 913, 1987), many studies have been conducted on
organic EL devices using organic materials as the constituting
materials. Tang et al used a laminate structure using
tris(8-hydroxyquinolinolato)aluminum for the light emitting layer
and a triphenyldiamine derivative for the hole transporting layer.
Advantages of the laminate structure are that the efficiency of
hole injection into the light emitting layer can be increased, that
the efficiency of forming excited particles which are formed by
blocking and recombining electrons injected from the cathode can be
increased, and that excited particles formed within the light
emitting layer can be enclosed. As the structure of the organic EL
device, a two-layered structure having a hole transporting
(injecting) layer and an electron transporting and light emitting
layer and a three-layered structure having a hole transporting
(injecting) layer, a light emitting layer and an electron
transporting (injecting) layer are well known. To increase the
efficiency of recombination of injected holes and electrons in the
devices of the laminate type, the structure of the device and the
process for forming the device have been studied.
[0004] As the hole injecting material used for the organic EL
device, high molecular weight amine compounds disclosed in Patent
Reference 1, triarylamine polymers disclosed in Patent Reference 2
and phenylenediamine derivatives disclosed in Patent Reference 3
have been known.
[0005] Injection of holes into the anode is facilitated since these
compounds have small ionization potentials and mobility of holes is
greater than that of star-burst amine derivatives such as the
compounds disclosed in Patent Reference 4. Therefore, these
compounds are suitable as the hole injecting material.
[0006] Materials used for an organic EL device can be divided into
low molecular weight organic materials used for preparing the
device in accordance with the vacuum vapor deposition process and
organic polymer materials used for preparing the device in
accordance with a coating process such as the spin coating process
and the ink-jet process using a solution of the materials dissolved
in a solvent. It is not always necessary that the polymer material
used above is a material having a great molecular weight, and
various materials can be used without problems as long as the
materials form the amorphous condition at the temperature of the
use. As such materials, materials called low molecular weight
amorphous materials are attracting attention.
[0007] Examples of the conventional low molecular weight hole
injecting and transporting material include the following
compounds: ##STR1## Among these compounds, TPD has been used widely
since the compound has an ionization potential as small as 5.4 eV
and exhibits a great mobility of holes. However, the compounds
shown above as the examples exhibit poor heat resistance (low glass
transition temperatures. Tg) and have a drawback in that
crystallization takes place after a long time even at the room
temperature, and the film becomes uneven.
[0008] As for the hole injecting and transporting polymers, the
hole injecting property can be improved by doping electrically
conductive polymers such as polythiophene and polyaniline with an
acid such as PSS having the structure shown below. Hole injecting
and transporting polymer into which TPD is introduced in the main
chain or in side chains have been studied.
[0009] Since an organic EL device using a polymer material can be
prepared without using a vacuum unlike those requiring the vacuum
vapor deposition, it is expected that thin films having an
excellent quality can be easily formed. This provides a great
advantage in the production process, and the advantageous
preparation of a device having a great area is expected. However,
there is a problem in that elution with a solvent takes place
during the coating for forming the hole injecting layer, the hole
transporting layer and the light emitting layer of the laminate
structure. PEDOT/PSS having the structure shown below is excellent
as the hole transporting layer since PEDOT/PSS is soluble in water
and insoluble in organic solvents. However, the life of light
emission is not always sufficient, and the improvement has been
desired. As the factors adversely affecting the life of light
emission, contamination with water and adverse effects of oxygen
atom and sulfur atom formed by decomposition are suspected.
##STR2##
[0010] [Patent Reference 1] Japanese Patent Application Laid-Open
No. Heisei 9(1997)-301934
[0011] [Patent Reference 2] International Patent Application
Laid-Open No. WO98/30071
[0012] [Patent Reference 3] Japanese Patent Application Laid-Open
No. 2000-309566
[0013] [Patent Reference 4] Japanese Patent Application Laid-Open
No. Heisei 4(1992)-308688
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Intention
[0014] The present invention has been made to overcome the above
problems and has an object of providing an organic EL device
exhibiting an excellent balance in physical properties such as a
small ionization potential a great band gap energy a great
efficiency of injection and a great mobility and excellent heat
resistance and efficiency of light emission and a novel amine-based
compound enabling to obtain the device.
MEANS FOR SOLVING THE PROBLEM
[0015] As the result of intensive studies by the present inventors
to achieve the above object, it was found that the above object
could be achieved by using an amine-based compound represented by
the following general formula (1) or (2) as the material for the
organic EL device. The present invention has been completed based
on the knowledge.
[0016] The present invention provides an amine-based compound
represented by following general formula (1) or (2): ##STR3##
wherein X represents a substituted or unsubstituted arylene group
having 4 to 50 carbon atoms, a heterocyclic crosslinking group or a
group represented by following general formula (3) or (4), a
plurality of X may represent a same group or different groups, and
at least one of the plurality of X in general formulae (1) and (2)
represents a group represented by following general formula (3) or
(4);
[0017] Y represents a substituted or unsubstituted aryl group
having 4 to 50 carbon atoms or a substituted or unsubstituted
heterocyclic group having 5 to 50 carbon atoms, and a plurality of
Y nay represent a same group or different groups;
[0018] n represents an integer of 0 to 3; and N represents nitrogen
atom; general formulae (3) and (4) being: ##STR4## wherein R.sup.1
and R.sup.2 each independently represent hydrogen atom, a halogen
atom, a substituted or unsubstituted alkyl group having 1 to 50
carbon atoms, a substituted or unsubstituted alkoxyl group having 1
to 50 carbon atoms, a substituted or unsubstituted aryloxyl group
having 4 to 50 carbon atoms, a substituted or unsubstituted
thioalkoxyl group having 1 to 50 carbon atoms, a substituted or
unsubstituted thioaryloxyl group having 4 to 50 carbon atoms, a
substituted or unsubstituted amino group, a substituted or
unsubstituted aryl group having 4 to 50 carbon atoms, a substituted
or unsubstituted alkylcarbonyl group having 1 to 50 carbon atoms or
a substituted or unsubstituted arylcarbonyl group having 4 to 50
carbon atoms; atoms and groups represented by R.sup.1 and R.sup.2
may be same with or different from each other, and adjacent groups
represented by R.sup.1 may be bonded to each other to form a cyclic
structure, and adjacent groups represented by R.sup.2 may be bonded
to each other to form a cyclic structure; and
[0019] Z represents sulfur atom, oxygen atom or --NR.sup.3--,
R.sup.3 representing hydrogen atom, a substituted or unsubstituted
aryl group having 4 to 50 carbon atoms, a substituted or
unsubstituted heterocyclic group having 5 to 50 carbon atoms or a
substituted or unsubstituted alkyl group having 1 to 50 carbon
atoms.
[0020] The present invention also provides an organic EL device
which comprises a cathode, an anode and an organic thin film layer
which comprises at least one layer comprising at least a light
emitting layer and is disposed between the cathode and the anode,
wherein at least one layer in the organic thin film layer comprises
the amine-based compound described above singly or as a component
of a mixture.
THE EFFECT OF THE INVENTION
[0021] The amine-based compound of the present invention is useful
as the hole injecting material and the hole transporting material
for organic EL devices and photo-sensitive materials for electronic
photography. The organic EL device using the amine-based compound
of the present invention exhibits an excellent balance in physical
properties such as a small ionization potential, a great band gap
energy, a great efficiency of injection and a great mobility and
excellent heat resistance and efficiency of light emission.
THE MOST PREFERRED EMBODIMENT TO CARRY OUT THE INVENTION
[0022] The amine-based compound of the present invention is
represented by the following general formula (1) or (2):
##STR5##
[0023] In general formulae 1) and (2), N represents nitrogen
atom.
[0024] In general formula (1) n represents an integer of 0 to 3 and
preferably 1.
[0025] In general formulae (1) and (2), Y represents a substituted
or unsubstituted aryl group having 4 to 50 carbon atoms or a
substituted or unsubstituted heterocyclic group having 5 to 50
carbon atoms, and a plurality of Y may represent the same group or
different groups.
[0026] Examples of the aryl group represented by Y include phenyl
group, substituted phenyl groups such as various types of tolyl
groups and various types of xylyl groups, 1-naphthyl group,
substituted 1-naphthyl groups such as various types of
methyl-substituted 1-naphthyl groups and various types of
dimethyl-substituted 1-naphthyl groups, 2-naphthyl group,
substituted 2-naphthyl groups such as various types of
methyl-substituted 2-naphthyl groups and various types of
dimethyl-substituted 2-naphthyl groups, (substituted) 1-anthryl
groups, (substituted) 2-anthryl groups, (substituted) 9-anthryl
groups, (substituted) 1-phenanthryl groups, substituted
2-phenanthryl groups, (substituted) 3-phenanthryl groups,
(substituted) 4-phenanthryl groups, (substituted) 9-phenanthryl
groups, (substituted) 1-naphthacenyl groups, (substituted)
2-naphthacenyl groups, (substituted) 9-naphthacenyl groups,
(substituted) 1-pyrenyl groups, (substituted) 2-pyrenyl groups and
(substituted) 4-pyrenyl groups. Among these groups, (substituted)
phenyl groups and (substituted) naphthyl groups are preferable.
[0027] The substituent to the above groups is not limited to
hydrocarbon groups but may be groups having a heteroatom such as
alkoxyl groups, carboxyl group, carboxyester groups, aryloxyl
groups, dialkylamino groups, diarylamino groups and thioalkoxyl
groups. The atoms constituting the nucleus are not limited to
carbon atoms and may contain a heteroatom such as oxygen atom
(furyl group and the like), nitrogen atom (pyridyl group, pyrrolyl
group and the like), boron atom (boraphenyl group and the like),
silicon atom (silaphenyl group and the like) and sulfur atom
(thiofuryl group and the like).
[0028] Examples of the heterocyclic group represented by Y include
pyridinyl group pyrazinyl group, pyrimidinyl group, pyridazinyl
group, triazinyl group, indolinyl group, quinolinyl group acridinyl
group, pyrrolidinyl group, dioxanyl group, piperidinyl group,
morpholidinyl group, piperazinyl group, triatinyl group, carbazolyl
group, furanyl group, thiophenyl group, oxazolyl group, oxadiazolyl
group, benzoxazolyl group, thiazolyl group, thiadiazolyl group,
benzothiazolyl group, triazolyl group, imidazolyl group,
benzimidazolyl group and purinyl group. The above groups may have
substituents. Examples of the substituent include substituents
described above as the examples of the substituent to the aryl
group.
[0029] In general formulae (1) and (2), X represents a substituted
or unsubstituted arylene group having 4 to 50 carbon atoms a hetero
cyclic crosslinking group or a group represented by the following
general formula (3) or (4), a plurality of X may represent the same
group or different groups, and at least one of the plurality of X
in general formulae (1) and (2) represents a group represented by
the following general formula (3) or (4).
[0030] Examples of the arylene group represented by X include
phenylene group, substituted phenylene groups such as various types
of tolylene group and various types of xylylene group, various
types of naphthylene groups, substituted naphthylene groups such as
various types of methyl-substituted naphthylene groups and various
types of dimethyl-substituted naphthylene groups, various types of
(substituted) anthrylene groups, various types of (substituted)
phenanthrylene groups, various types (substituted)
1-naphthacenylene groups and various types of (substitute d)
pyrenylene groups. Among these groups, (substituted) phenylene
groups and (substituted) naphthylene groups are preferable.
[0031] The positions of the crosslinking are not particularly
limited. It is preferable that the crosslinking is formed at the 1-
and 4-positions.
[0032] Examples of the heterocyclic crosslinking group represented
by X include (substituted) pyridinylene groups, (substituted)
pyrrolylene groups, (substituted) thiophenylene groups and
(substituted) furanylene groups. Among these groups, (substituted)
pyridinylene groups, (substituted) pyrrolylene groups and
(substituted) thiophenylene groups are preferable, and
(substituted) pyridinylene groups crosslinked at the 2,5-positions,
(substituted) pyrrolylene groups crosslinked at the 2,5-positions
and (substituted) thiophenylene groups crosslinked at the
2,5-positions are more preferable.
[0033] The substituent to the above groups is not limited to
hydrocarbon groups but may be groups having a heteroatom such as
alkoxylene groups, carboxyester groups, aryloxylene groups,
dialkylamino groups, and thioalkoxylene groups. The atoms
constituting the nucleus are not limited to carbon atoms and may
contain a heteroatom such as oxygen atom (furylene group and the
like), nitrogen atom (pyridylene group, pyrrolylene group and the
like), boron atom (boraphenylene group and the like), silicon atom
(silaphenylene group and the like) and sulfur atom (thiofurylene
group and the like).
[0034] General formulae (3) and (4) are shown in the following:
##STR6##
[0035] In general formulae (3) and (4), R.sup.1 and R.sup.2 each
independently represent hydrogen atom, a halogen atom, a
substituted or unsubstituted alkyl group having 1 to 50 carbon
atoms, a substituted or unsubstituted alkoxyl group having 1 to 50
carbon atoms, a substituted or unsubstituted aryloxyl group having
4 to 50 carbon atoms, a substituted or unsubstituted thioalkoxyl
group having 1 to 50 carbon atoms, a substituted or unsubstituted
thioaryloxyl group having 4 to 50 carbon atoms, a substituted or
unsubstituted amino group, a substituted or unsubstituted aryl
group having 4 to 50 carbon atoms, a substituted or unsubstituted
alkylcarbonyl group having 1 to 50 carbon atoms or a substituted or
unsubstituted arylcarbonyl group having 4 to 50 carbon atoms. Atoms
or groups represented by R.sup.1 and R.sup.2 ray be the same with
or different from each other. Adjacent groups represented by
R.sup.1 may be bonded to each other to form a cyclic structure, and
adjacent groups represented by R.sup.2 may be bonded to each other
to form a cyclic structure.
[0036] Examples of the halogen atom represented by R.sup.1 and
R.sup.2 include fluorine atom, chlorine atom, bromine atom and
iodine atom.
[0037] Examples of the alkyl group represented by R.sup.1 and
R.sup.2 include methyl group, ethyl group, propyl group, isopropyl
group, n-butyl group, s-butyl group, isobutyl group, t-butyl group,
n-pentyl group, n-hexyl group, n-heptyl group and n-octyl
group.
[0038] Examples of the aryl group represented by R.sup.1 and
R.sup.2 include phenyl group, substituted phenyl groups such as
various types of tolyl groups and various types of xylyl groups,
1-naphthyl group, substituted 1-naphthyl groups such as various
types of methyl-substituted 1-naphthyl groups and various types of
dimethyl-substituted 1-naphthyl groups, 2-naphthyl group,
substituted 2-naphthyl groups such as various types of
methyl-substituted 2-naphthyl groups and various types of
dimethyl-substituted 2-naphthyl groups, (substituted) 1-anthryl
groups, (substituted) 2-anthryl groups, (substituted) 9-anthryl
groups (substituted) 1-phenanthryl groups, (substituted)
2-phenanthryl groups (substituted) 3-phenanthryl groups,
(substituted) 4-phenanthryl groups, (substituted) 9-phenanthryl
groups, (substituted) 1-naphthacenyl groups, (substituted)
2-naphthacenyl groups, (substituted) 9-naphthacenyl groups,
(substituted) 1-pyrenyl groups, (substituted) 2-pyrenyl groups and
(substituted) 4-pyrenyl groups.
[0039] The alkoxyl group represented by R.sup.1 and R.sup.2 is
represented by RO--. Examples of the group represented by R include
the groups described above as the examples of the alkyl group.
[0040] The aryloxyl group represented by R.sup.1 and R.sup.2 is
represented by R'O--. Examples of the group represented by R'
include the groups described above as the examples of the aryl
group.
[0041] Examples of the thioalkoxyl group represented by R.sup.1 and
R.sup.2 include the groups similar to those described above as the
examples of the alkoxyl group.
[0042] Examples of the thioaryloxyl group represented by R.sup.1
and R.sup.2 include the groups similar to those described above as
the examples of the aryloxyl group.
[0043] Examples of the amino group represented by R.sup.1 and
R.sup.2 include diphenylamino group, ditolylamino group,
dinaphthylamino group, naphthylphenylaminio group, dimethylamino
group, diethylamino group and dihexylamino group.
[0044] The alkylcarbonyl group represented by R.sup.1 and R.sup.2
is represented by RCO--. Examples of the group represented by R
include the groups described above as the examples of the alkyl
group.
[0045] The arylcarbonyl group represented by R.sup.1 and R.sup.2 is
represented by R'CO--. Examples of the group represented by R'
include the groups described above as the examples of the aryl
group.
[0046] When adjacent groups represented by a plurality of R.sup.1
or R.sup.2 are bonded to each other to form a cyclic structure,
examples of the group include (substituted) 1,1-biphenylene groups,
(substituted) 1,5-naphthylene groups, (substituted) 4-butylene
groups and substituted) 1,4-butadienylene groups.
[0047] In general formula (4), Z represents sulfur atom, oxygen
atom or --NR.sup.3--, wherein R.sup.3 represents hydrogen atom, a
substituted or unsubstituted aryl group having 4 to 50 carbon
atoms, a substituted or unsubstituted heterocyclic group having 5
to 50 carbon atoms or a substituted or unsubstituted alkyl group
having 1 to 50 carbon atoms.
[0048] Examples of the aryl group, the heterocyclic group and the
alkyl group represented by R.sup.3 include the corresponding groups
described above as the examples of the aryl group, the heterocyclic
group and the alkyl group, respectively.
[0049] Specific examples of the amine-based compound represented by
general formula (1) or (2), which is the amine-based compound of
the present invention, are shown in the following. However, the
amine-based compound is not limited to the compounds shown as the
examples. ##STR7## ##STR8## ##STR9## ##STR10## ##STR11## ##STR12##
##STR13## ##STR14## ##STR15##
[0050] The process for producing the amine-based compound of the
present invention will be described in the following,
[0051] The amine-based compound of the present invention can be
produced in accordance with a conventional process (the reference
is, for example, Yuki Gosei Kagaku Kyokai Shi, Volume 59, Number 6,
2001 Page 607). Processes for synthesis [1] to [4] for typical
groups of the compounds are shown in the following. However, the
process for the synthesis is not limited to the processes shown as
the examples. ##STR16## ##STR17## ##STR18## ##STR19##
[0052] Compounds and reagents used in processes of synthesis [1] to
[4] will be described in the following.
[0053] In Compounds a to c, amines a to c and Compounds A to C, N
represents nitrogen atom, and X, Y R.sup.1 and R.sup.2 are as
defined above. A represents a halogen atom, preferably iodine atom,
bromine atom or chlorine atom and more preferably bromine atom.
[0054] The transition metal compound is a compound having a
transition atom selected from metals of Group 8, Group 9 and Group
10 of the Periodic Table, preferably a compound having a transition
metal selected from metals of Group 10 and more preferably a
compound having palladium. Specific examples include PdCl.sub.2,
Pd(OAc).sub.2 (Ac: acetyl group), Pd.sub.2(dba).sub.3 (dba:
dibenzylyleneacetone), BINAP
(2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) and DPPF
(1,1'-bis(diphenylphosphino)ferrocene).
[0055] The ligand is a compound having an element of Group 15 or
Group 16, preferably a compound having an element of Group 15 and
more preferably a compound having phosphorus. Specific examples of
the ligand include PAr.sub.3 (Ar: an aryl group) such as
P(o-Tol).sub.3 (Tol tolyl group) and PPh.sub.3 (Ph: phenyl group)
and PR.sub.3 (R: an alkyl group) such as PCy.sub.3 (Cy: cyclohexyl
group) and PtBu.sub.3.
[0056] The base is a compound comprising an alkali metal and a
conjugate base or an alkaline earth metal and a conjugate base, and
any base can be used as long as hydrogen atom in the amine used for
the reaction can be dissociated as proton. A conjugate base of a
basic compound having an acid dissociation constant (a pKa value)
of 18 or greater (at 25.degree. C. in water) is preferable.
[0057] As the alkali metal, lithium and sodium are preferable and,
as the alkaline earth metal, magnesium is preferable.
[0058] Examples of the conjugate base of a basic compound having an
acid dissociation constant (a pKa value) of 18 or greater (at
25.degree. C. in water) include --N(SiR.sub.3).sub.2, --NR.sub.2
and --OR(R: an alkyl group). Among these bases,
--N(SiMe.sub.3).sub.2 (Me: methyl group), --N(isopropyl).sub.2 and
-OtBu are preferable.
[0059] The solvent is not particularly limited as long as the
solvent does not react with the compound of the transition metal,
the ligand or the base. Aromatic solvents such as xylenes and
toluene are preferable.
[0060] The temperature of the reaction is not particularly limited.
The temperature is, in general, in the range of the room
temperature to 200.degree. C. or to the boiling point of the
solvent and preferably in the range of the room temperature to
120.degree. C.
[0061] The time of the reaction is not particularly limited. The
time is, in general, 1 to 150 hours and preferably 3 to 100
hours.
[0062] The relative amounts of the reactants are not particularly
limited. The ratio of the amounts by mole of Compounds a b or c
amine a, b or c the compound of the transition metal the ligand:
the base is, in general,
100:180.about.300:0.1.about.10:0.1.about.40:150.about.300 and
preferably
100:190.about.220:0.5.about.5:1.about.10:180.about.250.
[0063] The concentration of the reaction fluid is not particularly
limited. The concentration of the reaction fluid expressed as the
concentration of Compound a, b or c is, in general, 0.01 to 2
moles/liter and preferably 0.1 to 0.2 moles/liter.
[0064] The amine-based compound of the present invention is
suitable for the hole injecting material and the hole transporting
material and can be used in a wide area of applications as the
material for the solar batteries, photo-sensitive materials for
electronic photography and organic EL devices. In particular, the
amine-based compound is suitable for the hole injecting material
and the hole transporting material of organic EL devices.
[0065] The organic electroluminescence device of the present
invention comprises a cathode, an anode and an organic thin film
layer which comprises at least one layer comprising at least a
light emitting layer and is disposed between the cathode and the
anode, wherein at least one layer in the organic thin film layer
comprises the amine-based compound of the present invention singly
or as a component of a mixture.
[0066] It is preferable that, in the organic EL device of the
present invention, the organic thin film layer comprises a hole
injecting layer and/or a hole transporting layer, and the hole
injecting layer and/or the hole transporting layer comprises the
amine-based compound of the present invention singly or as a
component of a mixture.
[0067] The construction of the organic EL device of the present
invention will be described in the following.
[0068] Typical examples of the construction of the organic EL
device include:
(1) An anode/a light emitting layer/a cathode;
(2) An anode/a hole injecting layer/a light emitting layer/a
cathode;
(3) An anode/a light emitting layer/an electron injecting layer/a
cathode;
(4) An anode/a hole injecting layer/a light emitting layer/an
electron injecting layer/a cathode;
(5) An anode/an organic semiconductor layer/a light emitting
layer/a cathode;
(6) An anode/an organic semiconductor layer/an electron barrier
layer/a light emitting layer/a cathode;
(7) An anode/an organic semiconductor layer/a light emitting
layer/an adhesion improving layer/a cathode;
(8) An anode/a hole injecting layer/a hole transporting layer/a
light emitting layer/an electron injecting layer/a cathode;
(9) An anode/an insulating layer/a light emitting layer/an
insulating layer/a cathode;
(10) An anode/an inorganic semiconductor layer/an insulating
layer/a light emitting layer/an insulating layer/a cathode;
(11) An anode/an organic semiconductor layer/an insulating layer/a
light emitting layer/an insulating layer/a cathode;
(12) An anode/an insulating layer/a hole injecting layer/a hole
transporting layer/a light emitting layer/an insulating layer/a
cathode; and
(13) An anode/an insulating layer/a hole injecting layer/a hole
transporting layer/a light emitting layer/an electron injecting
layer/a cathode.
[0069] Among the above constructions, construction (8) is
preferable. However, the construction of the organic EL device is
not limited to those shown above as the examples.
[0070] It is preferable that the light emitting zone or the hole
transporting zone comprises the amine-based compound of the present
invention among the constituting elements of the device although
any of the organic layers may comprise the amine-based compound. It
is more preferable that the hole injecting zone comprises the
amine-based compound.
[0071] In the organic EL device of the present invention, the light
emitting layer may have a single layer or a plurality of layers,
and it is preferable that the light emitting layer comprises the
amine-based compound of the present invention an amount in the
range of 30 to 100% by mole.
[0072] The organic EL device is, in general, prepared on a
substrate transmitting light. The substrate transmitting light is
the substrate supporting the organic EL device. It is preferable
that the substrate transmitting light has a transmittance of light
of 50% or greater in the visible region of 400 to 700 nm. It is
also preferable that a flat and smooth substrate is used.
[0073] As the substrate transmitting light for example, glass
plates and synthetic resin plates are advantageously used. Examples
of the glass plate include plates made of soda lime glass, glass
containing barium and strontium lead glass aluminosilicate glass
borosilicate glass barium borosilicate glass and quartz Examples of
the synthetic resin plate include plates made of polycarbonate
resins, acrylic resins, polyethylene terephthalate resins,
polyether sulfide resins and polysulfone resins.
[0074] The anode has the function of injecting holes into the hole
transporting layer or the light emitting layer. It is effective
that the anode has a work function of 4.5 eV or greater. Examples
of the material for the anode used in the present invention include
indium tin oxide alloys (ITO), indium-zinc alloys (IZO), tin oxide
(NESA), gold, silver, platinum and copper. For the cathode,
materials having a small work function are preferable for the
purpose of injecting electrons into the electron transporting layer
or the light emitting layer.
[0075] The anode can be prepared by forming a thin film of the
above electrode material in accordance with a process such as the
vapor deposition process and the sputtering process.
[0076] When the light emitted from the light emitting layer is
obtained through the anode, it is preferable that the anode has a
transmittance of the emitted light greater than 10%. It is also
preferable that the sheet resistivity of the anode is several
hundred .OMEGA./.quadrature. or smaller. The thickness of the anode
is in general, selected in the range of 10 nm to 1 .mu.m and
preferably in the range of 10 to 200 nm although the thickness may
be different depending on the used material.
[0077] The light emitting layer in the organic EL device of the
present invention has the following functions:
(i) The injecting function: the function of injecting holes from
the anode or the hole injecting layer and injecting electrons from
the cathode or the electron injecting layer when an electric field
is applied;
(ii) The transporting function: the function of transporting
injected charges (electrons and holes) by the force of the electric
field; and
[0078] (iii) The light emitting function: the function of providing
the field for recombination of electrons and holes and leading the
recombination to the emission of light. The easiness of injection
of holes and the easiness of injection of electrons may be
different. The ability of transportation expressed by the mobility
may be different between holes and electrons. It is preferable that
one of the charges is transferred.
[0079] As the process for forming the light emitting layer, a
conventional process such as the vapor deposition process, the spin
coating process and the LB process can be used. It is preferable
that the light emitting layer is a molecular deposit film.
[0080] The molecular deposit film is a thin film formed by
deposition of a material compound in the gas phase or a thin film
formed by solidification of a material compound in a solution or in
the liquid phase. In general, the molecular deposit film can be
distinguished from the thin film formed in accordance with the LB
process (the molecular accumulation film) based on the differences
in aggregation structures and higher order structures and the
functional differences caused by these structural differences.
[0081] As disclosed in Japanese Patent Application Laid-Open No.
Showa 57(1982)-51781, the light emitting layer can also be formed
by dissolving a binder such as a resin and the material compounds
into a solvent to prepare a solution, followed by forming a thin
film from the prepared solution in accordance with the spin coating
process or the like.
[0082] In the present invention, where desired, the light emitting
layer may comprise conventional light emitting materials other than
the light emitting material comprising the amine-based compound of
the present invention, or a light emitting layer comprising other
conventional light emitting material may be laminated to the light
emitting layer comprising the light emitting material of the
present invention as long as the object of the present invention is
not adversely affected.
[0083] In organic EL device of the present invention, it is
preferable that the light emitting layer is a layer emitting bluish
light. It is preferable that light emitting layer has a maximum
wavelength of the light emission of 450 to 500 nm and comprises a
host material and a bluish dopant.
[0084] As the host material in the light emitting layer, styryl
derivatives, arylene derivatives and aromatic amines (amine
derivatives) are preferable.
[0085] It is preferable that the styryl derivative is at least one
compound selected from distyryl derivatives, tristyryl derivatives,
tetrastyryl derivatives and styrylamine derivatives.
[0086] It is preferable that the arylene derivative is an
anthracene derivative and more preferably a compound having a
skeleton structure of an arylanthracene.
[0087] It is preferable that the aromatic amine is a compound
having 2 to 4 nitrogen atoms substituted with an aromatic group and
more preferably a compound having 2 to 4 nitrogen atoms substituted
with an aromatic group and at least one alkenyl group.
[0088] Examples of the styryl derivative and the anthracene
derivative include compounds represented by the following general
formulae [1] to [6]. Examples of the aromatic amine include
compounds represented by the following general formulae [7] and
[8]. ##STR20##
[0089] In the above general formula [1], R.sup.1 to R.sup.8 each
independently represent hydrogen atom, a halogen atom, cyano group,
nitro group, a substituted or unsubstituted alkyl group having 1 to
20 carbon atoms, a substituted or unsubstituted alkoxyl group
having 1 to 20 carbon atoms, a substituted or unsubstituted
aryloxyl group having 6 to 30 carbon atoms, a substituted or
unsubstituted alkylthio group having 1 to 20 carbon atoms, a
substituted or unsubstituted arylthio group having 6 to 30 carbon
atoms, a substituted or unsubstituted arylalkyl group having 7 to
30 carbon atoms, an substituted monocyclic group having 5 to 30
carbon atoms, a substituted or unsubstituted condensed polycyclic
group having 10 to 30 carbon atoms or a substituted or
unsubstituted heterocyclic group having 5 to 30 carbon atoms.
Ar.sup.1 and Ar.sup.2 each independently represent a substituted or
unsubstituted aryl group having 6 to 30 carbon atoms or a
substituted or unsubstituted alkenyl group. The substituent is a
substituted or unsubstituted alkyl group having 1 to 20 carbon
atoms, a substituted or unsubstituted alkoxyl group having 1 to 20
carbon atoms, a substituted or unsubstituted aryloxyl group having
6 to 30 carbon atoms, a substituted or unsubstituted alkylthio
group having 1 to 20 carbon atoms, a substituted or unsubstituted
arylthio group having 6 to 30 carbon atoms, a substituted or
unsubstituted arylalkyl group having 6 to 30 carbon atoms, an
unsubstituted monocyclic group having 5 to 30 carbon atoms, a
substituted or unsubstituted condensed polycyclic group having 10
to 30 carbon atoms or a substituted or unsubstituted heterocyclic
group having 5 to 30 carbon atoms. ##STR21##
[0090] In the above general formula [2], R.sup.1 to R.sup.10 each
independently represent hydrogen atom, a halogen atom, cyano group
nitro group, a substituted or unsubstituted alkyl group having 1 to
20 carbon atoms, a substituted or unsubstituted alkoxyl group
having 1 to 20 carbon atoms, a substituted or unsubstituted
aryloxyl group having 6 to 30 carbon atoms, a substituted or
unsubstituted alkylthio group having 1 to 20 carbon atoms, a
substituted or unsubstituted arylthio group having 6 to 30 carbon
atoms, a substituted or unsubstituted arylalkyl group having 7 to
30 carbon atoms, an unsubstituted monocyclic group having 5 to 30
carbon atoms, a substituted or unsubstituted condensed polycyclic
group having 10 to 30 carbon atoms or a substituted or
unsubstituted heterocyclic group having 5 to 30 carbon atoms.
Ar.sup.1 and Ar.sup.2 each independently represent a substituted or
unsubstituted aryl group having 6 to 30 carbon atoms or a
substituted or unsubstituted alkenyl group. The substituent is a
substituted or unsubstituted alkyl group having 1 to 20 carbon
atoms, a substituted or unsubstituted alkoxyl group having 1 to 20
carbon atoms, a substituted or unsubstituted aryloxyl group having
6 to 30 carbon atoms, a substituted or unsubstituted alkylthio
group having 1 to 20 carbon atoms, a substituted or unsubstituted
arylthio group having 6 to 30 carbon atoms, a substituted or
unsubstituted arylalkyl group having 6 to 30 carbon atoms, an
unsubstituted monocyclic group having 5 to 30 carbon atoms, a
substituted or unsubstituted condensed polycyclic group having 10
to 30 carbon atoms or a substituted or unsubstituted heterocyclic
group having 5 to 30 carbon atoms. ##STR22##
[0091] In the above general formula [3], R.sup.1 to R.sup.10 each
independently represent hydrogen atom, a halogen atom, cyano group,
nitro group, a substituted or unsubstituted alkyl group having 1 to
20 carbon atoms, a substituted or unsubstituted alkoxyl group
having 1 to 20 carbon atoms, a substituted or unsubstituted
aryloxyl group having 6 to 30 carbon atoms, a substituted or
unsubstituted alkylthio group having 1 to 20 carbon atoms, a
substituted or unsubstituted arylthio group having 6 to 30 carbon
atoms, a substituted or unsubstituted arylalkyl group having 7 to
30 carbon atoms, an unsubstituted monocyclic group having 5 to 30
carbon atoms, a substituted or unsubstituted condensed polycyclic
group having 10 to 30 carbon atoms or a substituted or
unsubstituted heterocyclic group having 5 to 30 carbon atoms.
Ar.sup.3 and Ar.sup.4 each independently represent a substituted or
unsubstituted aryl group having 6 to 30 carbon atoms or a
substituted or unsubstituted alkenyl group. The substituent is a
substituted or unsubstituted alkyl group having 1 to 20 carbon
atoms, a substituted or unsubstituted alkoxyl group having 1 to 20
carbon atoms, a substituted or unsubstituted aryloxyl group having
6 to 30 carbon atoms, a substituted or unsubstituted alkylthio
group having 1 to 20 carbon atoms, a substituted or unsubstituted
arylthio group having 6 to 30 carbon atoms, a substituted or
unsubstituted arylalkyl group having 6 to 30 carbon atoms, an
unsubstituted monocyclic group having 5 to 30 carbon atoms, a
substituted or unsubstituted condensed polycyclic group having 10
to 30 carbon atoms, a substituted or unsubstituted heterocyclic
group having 5 to 30 carbon atoms or a substituted or unsubstituted
alkenyl group having 4 to 40 carbon atoms. n represents an integer
of 1 to 3, m represents an integer of 1 to 3, and n+m.ltoreq.2.
##STR23##
[0092] In the above general formula [4], R.sup.1 to R.sup.8 each
independently represent hydrogen atom, a halogen atom, cyano group,
nitro group, a substituted or unsubstituted alkyl group having 1 to
20 carbon atoms, a substituted or unsubstituted alkoxyl group
having 1 to 20 carbon atoms, a substituted or unsubstituted
aryloxyl group having 6 to 30 carbon atoms, a substituted or
unsubstituted alkylthio group having 1 to 20 carbon atoms, a
substituted or unsubstituted arylthio group having 6 to 30 carbon
atoms, a substituted or unsubstituted arylalkyl group having 7 to
30 carbon atoms, an unsubstituted monocyclic group having 5 to 30
carbon atoms, a substituted or unsubstituted condensed polycyclic
group having 10 to 30 carbon atoms or a substituted or
unsubstituted heterocyclic group having 5 to 30 carbon atoms.
Ar.sup.3 and Ar.sup.4 each independently represent a substituted or
unsubstituted aryl group having 6 to 30 carbon atoms or a
substituted or unsubstituted alkenyl group. The substituent is a
substituted or unsubstituted alkyl group having 1 to 20 carbon
atoms, a substituted or unsubstituted alkoxyl group having 1 to 20
carbon atoms, a substituted or unsubstituted aryloxyl group having
6 to 30 carbon atoms, a substituted or unsubstituted alkylthio
group having 1 to 20 carbon atoms, a substituted or unsubstituted
arylthio group having 6 to 30 carbon atoms, a substituted or
unsubstituted arylalkyl group having 6 to 30 carbon atoms, an
unsubstituted monocyclic group having 5 to 30 carbon atoms, a
substituted or unsubstituted condensed polycyclic group having 10
to 30 carbon atoms, a substituted or unsubstituted heterocyclic
group having 1 to 30 carbon atoms or a substituted or unsubstituted
alkenyl group having 4 to 40 carbon atoms. ##STR24##
[0093] In the above general formula [5], R.sup.11 to R.sup.20 each
independently represent hydrogen atom, an alkenyl group, an alkyl
group, a cycloalkyl group, an aryl group, an alkoxyl group, an
aryloxyl group, an alkylamino group, an arylamino group or a
heterocyclic group which may be substituted. a and b each represent
an integer of 1 to 5. When a or b represent an integer of 2 or
greater, atoms and groups represented by the plurality of R.sup.11
or R.sup.12, respectively, may be the same with or different from
each other, and the groups represented by R.sup.11 or R.sup.12,
respectively, may be bonded to each other to form a ring. Groups
represented by the pair of R.sup.13 and R.sup.14, the pair of
R.sup.15 and R.sup.16, the pair of R.sup.17 and R.sup.18 or the
pair of R.sup.19 and R.sup.20 may be bonded to each other to form a
ring. L.sup.1 represents the single bond, --O--, --S--, --N(R), R
representing an alkyl group or an aryl group which may be
substituted, or an arylene group. ##STR25##
[0094] In the above general formula [6], R.sup.21 to R.sup.30 each
independently represent hydrogen atom, an alkenyl group, an alkyl
group, a cycloalkyl group, an aryl group, an alkoxyl group, an
aryloxyl group, an alkylamino group, an arylamino group or a
heterocyclic group which may be substituted. c, d, e and f each
represent an integer of 1 to 5. When c, d, e or f represent an
integer of 2 or greater, atoms and groups represented by the
plurality of R.sup.21, R.sup.22, R.sup.26 or R.sup.27,
respectively, may be the same with or different from each other,
and the groups represented by R.sup.21, R.sup.22, R.sup.26 or
R.sup.27, respectively, may be bonded to each other to form a ring.
Groups represented by the pair of R.sup.23 and R.sup.24 or the pair
of R.sup.28 and R.sup.29 may be bonded to each other to form a
ring. L.sup.2 represents the single bond, --O--, --S--, --N(R)--, R
representing an alkyl group or an aryl group which may be
substituted, or an arylene group. ##STR26##
[0095] In the above general formula [7], Ar.sup.5, Ar.sup.6 and
Ar.sup.7 each independently represent a substituted or
unsubstituted monovalent aromatic group having 6 to 40 carbon atoms
or styryl group, and g represent an integer of 1 to 4.
##STR27##
[0096] In the above general formula [8], Ar.sup.8, Ar.sup.9,
Ar.sup.11, Ar.sup.13 and Ar.sup.14 each independently represent a
substituted or unsubstituted monovalent aromatic group having 6 to
40 carbon atoms or styryl group, Ar.sup.10 and Ar.sup.12 each
independently represent a substituted or unsubstituted divalent
aromatic group having 6 to 40 carbon atoms or styrylene group, h
and k each represent an integer of 0 to 2, and i and j reach
represent an integer of 0 to 3.
[0097] As the dopant described above in the light emitting layer,
at least one compound selected from amine derivatives such as
styrylamine, styryl compounds substituted with an amine and
compounds having a condensed aromatic ring is preferable. Examples
of the styrylamine and styryl compound substituted with an amine
include compounds represented by the following general formulae [9]
and [10]. Examples of the compound having a condensed aromatic ring
include compounds represented by the following general formula
[11]. ##STR28##
[0098] In the above general formula [9], Ar.sup.5, Ar.sup.6 and
Ar.sup.7 each independently represent a substituted or
unsubstituted aromatic group having 6 to 40 carbon atoms or styryl
group, and p represents an integer of 1 to 3. ##STR29##
[0099] In the above general formula [10], Ar.sup.15 and Ar.sup.16
each independently represent an arylene group having 6 to 30 carbon
atoms, E.sup.1 and E.sup.2 each independently represent an aryl
group having 6 to 30 carbon atoms, an alkyl group, hydrogen atom or
cyano group, q represents an integer of 1 to 3, and U and/or V
represents a substituent having an amino group, the amino group
being preferably an arylamino group. (A).sub.r-B [11]
[0100] In the above general formula [1], A represents an alkyl
group or alkoxyl group having 1 to 16 carbon atoms, a substituted
or unsubstituted aryl group having 6 to 30 carbon atoms, a
substituted or unsubstituted alkylamino group having 6 to 30 carbon
atoms or a substituted or unsubstituted arylamino group having 6 to
30 carbon atoms, B represents a condensed aromatic cyclic group
having 10 to 40 carbon atoms, and r represents an integer of 1 to
4.
[0101] In the organic EL device of the present invention, a
phosphorescent compound may be used in the light emitting layer. It
is preferable that the host material comprising a phosphorescent
compound is a compound having carbazole ring.
[0102] The host material comprising the compound having carbazole
ring which is suitable for emission of phosphorescent light is a
compound having a function such that the phosphorescent compound
emits light as the result of transfer of energy to the
phosphorescent compound from the host compound in the excited
state. The host compound is not particularly limited as long as the
energy of the excimer can be transferred to the phosphorescent
compound and can be suitably selected in accordance with the
object. The host compound may have any desired heterocyclic ring in
combination with carbazole ring.
[0103] Examples of the host compound include carbazole derivatives,
triazole derivatives, oxazole derivatives, oxadiazole derivatives,
imidazole derivatives, polyarylalkane derivatives, pyrazoline
derivatives, pyrazolone derivatives, phenylenediamine derivatives,
arylamine derivatives, amino-substituted chalcone derivatives,
styrylanthracene derivatives, fluorenone derivatives, hydrazone
derivatives, stilbene derivatives, silazane derivatives, aromatic
tertiary amine compounds, styrylamine compounds, aromatic
dimethylidene-based compounds, porphyrin-based compounds,
anthraquinodimethane derivatives, anthrone derivatives,
diphenylquinone derivatives, thiopyrane dioxide derivatives,
carbodiimide derivatives, fluorenylidenemethane derivatives,
distyrylpyrazine derivatives, anhydrides of heterocyclic
tetracarboxylic acid such as acids derived from naphthalene and
perylene, phthalocyanine derivatives, various metal complexes such
as metal complexes of 8-quinolinol, metal phthalocyanines and metal
complexes using benzoxazole or benzothiazole as the ligand,
polysilane-based compounds, poly(N-vinylcarbazole) derivatives,
electrically conductive macromolecular oligomers such as
aniline-based copolymers, thiophene oligomers and polythiophene,
and polymer compounds such as polythiophene derivatives,
polyphenylene derivatives, polyphenylene-vinylene derivatives and
polyfluorene derivatives. The host compound may be used singly or
in combination of two or more.
[0104] Examples of the host compound include compounds shown in the
following: ##STR30## ##STR31##
[0105] As the dopant comprising a phosphorescent compound,
compounds which can emit light from the triplet excimers are
preferable. The dopant compound is not particularly limited as long
as light is emitted from the triplet excimers. Metal complexes
having at least one metal selected from Ir, Ru, Pd, Pt, Os and Re
are preferable. Porphyrin metal complexes and metal complexes in
the form of an ortho-metal are more preferable. As the porphyrin
metal complex, porphyrin platinum complexes are preferable. The
phosphorescent compound may be used singly or in combination of two
or more.
[0106] As the ligand for forming the metal complex in the form of
an ortho-metal, various ligands can be used. Preferable examples of
the ligand include 2-phenylpyridine derivatives, 7,8-benzoquinoline
derivatives, 2-(2-thienyl)pyridine derivatives, 2-(1
naphthyl)pyridine derivatives and 2-phenylquinoline derivatives.
These derivatives may have substituents, where necessary. As the
bluish dopant, fluorides and derivatives having trifluoromethyl
group introduced therein are preferable. The complexes may have
ligands other than those described above such as acetylacetone and
picric acid as the auxiliary ligand.
[0107] The content of the phosphorescent dopant in the light
emitting layer is not particularly limited and can be suitably
adjusted in accordance with the object. The content is, for
example, 0.1 to 70% by mass and preferably 1 to 30% by mass. When
the content of the phosphorescent dopant is smaller than 0.1% by
mass, the light emission is weak, and the effect of the
phosphorescent dopant is not sufficiently exhibited. When the
content of the phosphorescent dopant exceeds 70% by mass, the
phenomenon called concentration quenching becomes significant, and
the properties of the device deteriorate.
[0108] The light emitting layer may further comprise a hole
transporting material, an electron transporting material and a
binder, where necessary.
[0109] The thickness of the light emitting layer is preferably 5 to
50 nm, more preferably 7 to 50 nm and most preferably 10 to 50 nm.
When the thickness is 5 nm or greater, the formation of the light
emitting layer and the adjustment of the chromaticity are
facilitated. When the thickness is 50 nm or smaller, there is no
possibility of an increase in the driving voltage.
[0110] The hole injecting and transporting layer is a layer which
helps injection of holes into the light emitting layer and
transports holes to the light emitting region. The layer exhibits a
great mobility of holes and, in general, has an ionization energy
as small as 5.5 eV or smaller. For the hole injecting and
transporting layer, a material which transports holes to the light
emitting layer under an electric field of a smaller strength is
preferable. A material which exhibits, for example, a mobility of
holes of at least 10.sup.-4 cm.sup.2/Vsec under application of an
electric field of 10.sup.4 to 10.sup.6 V/cm is preferable.
[0111] When the amine derivative having a hetero ring of the
present invention is used for the hole transporting zone (the hole
injecting and transporting layer), the compound of the present
invention may be used singly or as a mixture with other material to
form the hole injecting and transporting layer.
[0112] The material mixed with the aromatic amine derivative of the
present invention and used for forming the hole injecting and
transporting layer is not particularly limited as long as the
material has the preferable properties described above, and a
material can be selected as desired from materials which are
conventionally used as the charge transporting material of holes in
photoconductive materials and conventional materials which are used
for the hole injecting layer in organic EL devices.
[0113] Examples of the material for the hole injecting layer
described above include triazole derivatives (U.S. Pat. No.
3,112,197), oxadiazole derivatives (U.S. Pat. No. 3,189,447),
imidazole derivatives (Japanese Patent Application Publication No.
Showa 37(1962)-16096), polyarylalkane derivatives (U.S. Pat. Nos.
3,615,402, 3,820,989 and 3,542,544; Japanese Patent Application
Publication Nos. Showa 45(1970)-555 and Showa 51(1976)-10983; and
Japanese Patent Application Laid-Open Nos. Showa 51(1976)-93224,
Showa 55(1980)-17105, Showa 56(1981)-4148, Showa 55(1950)-103667,
Showa 55(1980)-156953 and Showa 56(1981)-36656); pyrazoline
derivatives and pyrazolone derivatives (U.S. Pat. Nos. 3,180,729
and 4,278,746; and Japanese Patent Application Laid-Open Nos. Showa
55(1980)-88064, Showa 55(1980)-88065, Showa 49(1974)-105537, Showa
55(1980)-51086, Showa 56(1981)-80051, Showa 56(1981)-88141, Showa
57(1982)-45545, Showa 54(1979)-112637 and Showa 55(1980)-74546);
phenylenediamine derivatives (U.S. Pat. No. 3,615,404; Japanese
Patent Application Publication Nos. Showa 51(1976)-10105, Showa
46(1971)-3712 and Showa 47(1972)-25336; and Japanese Patent
Application Laid-Open Nos. Showa 54(1979)-53435, Showa
54(1979)-110536 and Showa 54(1979)-119925); arylamine derivatives
(U.S. Pat. Nos. 3,567,450, 3,180,703, 3,240,597, 3,658,520,
4,232,103, 4,175,961 and 4,012,376; Japanese Patent Application
Publication Nos. Showa 49(1974)-35702 and Showa 39(1964)-27577;
Japanese Patent Application Laid-Open Nos. Showa 55(1980)-144250,
Showa 56(1981)-119132 and Showa 56(1981)-22437; and West German
Patent No. 1,110,518); chalcone derivatives substituted with amino
group (U.S. Pat. No. 3,526,501); oxazole derivatives (U.S. Pat. No.
3,257,203); styrylanthracene derivatives (Japanese Patent
Application Laid-Open Nos. Showa 56(1981)-46234); fluorenone
derivatives (Japanese Patent Application Laid-Open Nos. Showa
54(1979)-110837); hydrazone derivatives (U.S. Pat. No. 3,717,462;
and Japanese Patent Application Laid-Open Nos. Showa
54(1979)-59143, Showa 55(1980)-52063, Showa 55(1980)-52064, Showa
55(1980)-46760, Showa 55(1980)-85495, Showa 57(1982)-11350, Showa
57(1982)-148749 and Heisei 2(1990)-311591); stilbene derivatives
(Japanese Patent Application Laid-Open Nos. Showa 61(1986)-210363,
Showa 61(1986)-228451, Showa 61(1986)-14642, Showa 61(1986)-72255,
Showa 62(1987)-47646, Showa 62(1987)-36674, Showa 62(1987)-10652,
Showa 62(1987)-30255 Showa 60(1985)-93455, Showa 60(1985)-94462,
Showa 60(1985)-174749 and Showa 60(1985)-175052); silazane
derivatives (U.S. Pat. No. 4,950,950); polysilane-based compounds
(Japanese Patent Application Laid-Open No. Heisei 2(1990)-204996);
aniline-based copolymers (Japanese Patent Application Laid-Open No.
Heisei 2(1990)-282263); and electrically conductive macromolecular
oligomers (in particular, thiophene oligomers) disclosed in
Japanese Patent Application Laid-Open No. Heisei 1(1989)-211399
[0114] Besides the above materials which can be used as the
material for the hole injecting layer, porphyrin compounds
(compounds disclosed in Japanese Patent Application Laid-Open No.
Showa 63(1988)-295695); and aromatic tertiary amine compounds and
styrylamine compounds (U.S. Pat. No. 4,127,412 and Japanese Patent
Application Laid-Open Nos. Showa 53(1978)-27033, Showa
54(1979)-58445, Showa 54(1979)-149634, Showa 54(1979)-64299, Showa
55(1980)-79450. Showa 55(1980)-144250, Showa 56(1981)-119132, Showa
61(1986)-295558, Showa 61(1986)-98353 and Showa 63(1988)-295695)
are preferable, and the aromatic tertiary amines are more
preferable.
[0115] Further examples include compounds having two condensed
aromatic rings in the molecule which are described in the U.S. Pat.
No. 5,061,569 such as
4,4'-bis(N-(1-naphthyl)-N-phenylamino)biphenyl and a compound in
which three triphenylamine units are bonded together in a
star-burst shape, which is described in Japanese Patent Application
Laid-Open No. Heisei 4(1992)-308688, such as
4,4',4''-tris(N-(3-methylphenyl)-N-phenylamino)triphenylamine.
[0116] Besides the aromatic dimethylidene-based compounds described
as the material for the light emitting layer, inorganic compounds
such as Si of the p-type and SiC of the p-type can be used as the
material for the hole injecting layer.
[0117] The hole injecting and transporting layer can be formed by
preparing a thin film of the amine-based compound of the present
invention and/or the above compound in accordance with a
conventional process such as the vacuum vapor deposition process,
the spin coating process, the casting process and the LB process.
The thickness of the hole injecting and transporting layer is not
particularly limited. In general, the thickness is 5 nm to 5
.mu.m.
[0118] The organic semiconductor layer is a layer helping injection
of holes or electrons into the light emitting layer. As the organic
semiconductor layer, a layer having a conductivity of 10.sup.-10
S/cm or greater is preferable. As the material for the organic
semiconductor layer, oligomers containing thiophene can be used,
and conductive oligomers such as oligomers containing arylamine and
conductive dendrimers such as dendrimers containing arylamine,
which are disclosed in Japanese Patent Application Laid-Open No.
Heisei 8(1996)-193191, can also be used.
[0119] The electron injecting and transporting layer is a layer
which helps injection of electrons into the light emitting layer
and transports electrons to the light emitting region and exhibits
a great mobility of electrons.
[0120] It is known that, in an organic EL device, emitted light is
reflected at an electrode the cathode in the present case) and the
light emitted and obtained directly from the anode and the light
obtained after reflection at the electrode interfere with each
other. The thickness of the electron transporting layer is suitably
selected in the range of several nm to several .mu.m so that the
interference is effectively utilized. When the thickness is great,
it is preferable that the mobility of electrons is at least
10.sup.-5 cm.sup.2/Vs or greater under the application of an
electric field of 10.sup.4 to 10.sup.6 V/cm so that the increase in
the voltage is prevented.
[0121] As the material used for the electron injecting layer metal
complexes of 8-hydroxyquinoline and derivatives thereof and
oxadiazole derivatives are preferable. Examples of metal complexes
of 8-hydroxyqunoline and the derivative thereof include metal
chelated oxinoid compounds including chelate compounds of oxines
(in general, 8-quinolinol or 8-hydroxy-quinoline). For example,
tris(8-quinolinol)aluminum can be used as the electron injecting
material.
[0122] Examples of the oxadiazole derivative include electron
transfer compounds represented by the following general formulae:
##STR32##
[0123] In the above formulae Ar.sup.1, Ar.sup.2, Ar.sup.3,
Ar.sup.4, Ar.sup.5, Ar.sup.6 and Ar.sup.9 each represent a
substituted or unsubstituted aryl group and may represent the same
group or different groups Ar.sup.4, Ar.sup.7 and Ar.sup.8 each
represent a substituted or unsubstituted arylene group and may
represent the same group or different groups.
[0124] Examples of the aryl group include phenyl group, biphenyl
group, anthranyl group, perylenyl group and pyrenyl group. Examples
of the arylene group include phenylene group, naphthylene group,
biphenylene group, anthranylene group, perylenylene group and
pyrenylene group. Examples of the substituent include alkyl groups
having 1 to 10 carbon atoms, alkoxyl groups having 1 to 10 carbon
atoms and cyano group. As the electron transfer compound, compounds
which can form thin films are preferable.
[0125] Specific examples of the electron transfer compound include
the following compounds: ##STR33##
[0126] As the material which can be used for the electron injecting
layer and the electron transporting layer, compounds represented by
the following general formulae (A) to (E) can be used.
[0127] Heterocyclic derivatives having nitrogen atom represented by
general formula (A) or (B): ##STR34##
[0128] In the above general formulae (A) and (B), A.sup.1 to
A.sup.3 each independently represent nitrogen atom or carbon
atom.
[0129] Ar.sup.1 represents a substituted or unsubstituted aryl
group having 6 to 60 ring carbon atoms or a substituted or
unsubstituted heteroaryl group having 3 to 60 ring carbon atoms;
Ar.sup.2 represents hydrogen atom, a substituted or unsubstituted
aryl group having 6 to 60 ring carbon atoms, a substituted or
unsubstituted heteroaryl group having 3 to 60 ring carbon atoms, a
substituted or unsubstituted alkyl group having 1 to 20 carbon
atoms a substituted or unsubstituted alkoxyl group having 1 to 20
carbon atoms or a divalent group derived from any of the above
groups; and either one of Ar.sup.1 and Ar.sup.2 represents a
substituted or unsubstituted condensed cyclic group having 10 to 60
ring carbon atoms or a substituted or unsubstituted monohetero
condensed cyclic group having 3 to 60 ring carbon atoms.
[0130] L.sup.1, L.sup.2 and L each independently represent the
single bond, a substituted or unsubstituted arylene group having 6
to 60 ring carbon atoms, a substituted or unsubstituted
heteroarylene group having 3 to 60 ring carbon atoms or a
substituted or unsubstituted fluorenylene group.
[0131] R represents a hydrogen atom, a substituted or unsubstituted
aryl group having 6 to 60 ring carbon atoms, a substituted or
unsubstituted heteroaryl group having 3 to 60 ring carbon atoms, a
substituted or unsubstituted alkyl group having 1 to 20 carbon
atoms or a substituted or unsubstituted alkoxyl group having 1 to
20 carbon atoms; n represents an integer of 0 to 5; and, when n
represents an integer of 2 or greater, the atoms and the groups
represented by a plurality of IR may be the same with or different
from each other, and a plurality of groups represented by R which
are adjacent to each other may be bonded to each other to form an
aliphatic ring of the carbon ring type or an aromatic ring of the
carbon ring type.
[0132] Heterocyclic derivative having nitrogen atom represented by
the following general formula (C): HAr-L-Ar.sup.1--Ar.sup.2 (C)
[0133] In general formula (C), HAr represents a heterocyclic group
having 3 to 40 carbon atoms and nitrogen atom which may have
substituents, L represents the single bond or an arylene group
having 6 to 60 carbon atoms which may have substituents, a
heteroarylene group having 3 to 60 carbon atoms which may have
substituents or a fluorenylene group which may have substituents.
Ar.sup.1 represents a divalent aromatic hydrocarbon group having 6
to 60 carbon atoms which may have substituents, and Ar.sup.2
represents an aryl group having 6 to 60 carbon atoms which may have
substituents or a heteroaryl group having 3 to 60 carbon atoms
which may have substituents.
[0134] Silacyclopentadiene derivatives represented by the following
general formula (D): ##STR35##
[0135] In general formula (D), X and Y each independently represent
a saturated or unsaturated hydrocarbon group having 1 to 6 carbon
atoms, an alkoxyl group, an alkenyloxyl group, an alkynyloxyl
group, hydroxyl group, a substituted or unsubstituted aryl group, a
substituted or unsubstituted heterocyclic group or a saturated or
unsaturated cyclic group formed by bonding of the above groups
represented by X and Y; and R.sub.1 to R.sub.4 each independently
represent hydrogen atom, a halogen atom, a substituted or
unsubstituted alkyl group having 1 to 6 carbon atoms, an alkoxyl
group, an aryloxyl group, a perfluoroalkyl group, a
perfluoroalkoxyl group, an amino group, an alkylcarbonyl group, an
arylcarbonyl group, an alkoxycarbonyl group, an aryloxycarbonyl
group, an azo group, an alkylcarbonyloxyl group, an
arylcarbonyloxyl group, an alkoxycarbonyloxyl group, an
aryloxycarbonyloxyl group, sulfinyl group sulfonyl group, sulfanyl
group, silyl group, carbamoyl group, an aryl group, a heterocyclic
group, an alkenyl group, an alkynyl group, nitro group, formyl
group, nitroso group, formyloxyl group, isocyano group, cyanate
group, isocyanate group, thiocyanate group, isothiocyanate group, a
cyano group or, when the groups are adjacent to each other, a
structure formed by condensation of substituted or unsubstituted
rings.
[0136] Borane derivatives represented by the following general
formula (E): ##STR36##
[0137] In general formula (E), R.sub.1 to R.sub.8 and Z.sub.2 each
independently represent hydrogen atom, a saturated or unsaturated
hydrocarbon group, an aromatic group, a heterocyclic group, a
substituted amino group, a substituted boryl group, an alkoxyl
group or an aryloxyl group; X, Y and Z, each independently
represent a saturated or unsaturated hydrocarbon group, an aromatic
group, a heterocyclic group, a substituted amino group, an alkoxyl
group or an aryloxyl group, and substituents to the groups
represented by Z.sub.1 and Z.sub.2 may be bonded to each other to
form a condensed ring; n represents an integer of 1 to 3 and, when
n represents an integer of 2 or greater, a plurality of Z.sub.1 may
represent different groups; and the case where n represents 1, X, Y
and R.sub.2 each represent methyl group and R.sub.8 represents
hydrogen atom or a substituted boryl group and the case where n
represents 3 and Z.sub.1 represents methyl group are excluded.
[0138] Compounds represented by general formula (F): ##STR37##
[0139] In general formula (F), Q.sup.1 and Q.sup.2 each
independently represent a ligand represented by the following
general formula (G): ##STR38## (rings A.sup.1 and A.sup.2 each
representing a six-membered aryl cyclic structure which may have
substituents and are condensed with each other), L represents a
halogen atom, a substituted or unsubstituted alkyl group, a
substituted or unsubstituted cycloalkyl group, a substituted or
unsubstituted aryl group, a substituted or unsubstituted
heterocyclic group, --OR.sup.1 (R.sup.1 representing hydrogen atom,
a substituted or unsubstituted alkyl group, a substituted or
unsubstituted cycloalkyl group, a substituted or unsubstituted aryl
group or a substituted or unsubstituted heterocyclic group) or
--O--Ga-Q.sup.3(Q.sup.4) (Q.sup.3 and Q.sup.4 are as defined for
Q.sup.1 and Q.sup.2).
[0140] The above metal complex compound strongly exhibits the
property as the n-type semiconductor and a great ability of
electron injection. Since the energy of formation of the complex
compound is small, the bonding between the metal and the ligand in
the formed metal complex compound is strong, and the quantum
efficiency of fluorescence as the light emitting material is
great.
[0141] Examples of the substituent to rings A.sup.1 and A.sup.2
forming the ligand represented by general formula (G) include
halogen atoms such as chlorine atom, bromine atom, iodine atom and
fluorine atom; substituted and unsubstituted alkyl groups such as
methyl group, ethyl group, propyl group, butyl group, sec-butyl
group, tert-butyl group, pentyl group, hexyl group, heptyl group,
octyl group, stearyl group and trichloromethyl group; substituted
and unsubstituted aryl groups such as phenyl group, naphthyl group,
3-methylphenyl group, 3-methoxyphenyl group, 3-fluorophenyl group,
3-trichloromethylphenyl group, 3-trifluoromethylphenyl group and
3-nitrophenyl group; substituted and unsubstituted alkoxyl groups
such as methoxyl group, n-butoxyl group, tert-butoxyl group,
trichloromethoxyl group, trifluoroethoxyl group,
pentafluoropropoxyl group, 2,2,3,3-tetrafluoropropoxyl group,
1,1,1,3,3,3-hexafluoro-2-propoxyl group and
6-(perfluoroethyl)hexyloxyl group; substituted and unsubstituted
aryloxyl groups such as phenoxyl group, p-nitrophenoxyl group,
p-tert-butylphenoxyl group, 3-fluorophenoxyl group,
pentafluorophenoxyl group and 3-trifuoromethylphenoxyl group,
substituted and unsubstituted alkylthio groups such as methylthio
group, ethylthio group, tert-butylthio group, hexylthio group,
octylthio group and trifluoromethylthio group; substituted and
unsubstituted arylthio groups such as phenylthio group,
p-nitrophenylthio group, p-tert-butylphenylthio group,
3-fluorophenylthio group, pentafluorophenylthio group and
3-trifluoromethylphenylthio group; cyano group; nitro group; amino
group; mono- and disubstituted amino groups such as methylamino
group diethylamino group, ethylamino group, diethylamino group,
dipropylamino group, dibutylamino group and diphenylamino group;
acylamino groups such as bis(acetoxymethyl)amino group,
bis(acetoxyethyl)amino group, bis(acetoxypropyl)amino group and
bis(acetoxybutyl)amino group; hydroxyl group; siloxyl group; acyl
group; carbamoyl groups such as methylcarbamoyl group,
dimethylcarbamoyl group, ethylcarbamoyl group, diethylcarbamoyl
group, propylcarbamoyl group, butylcarbamoyl group and
phenylcarbamoyl group; carboxylic acid group; sulfonic acid group;
imide group; cycloalkyl groups such as cyclopentane group and
cyclohexyl group; aryl groups such as phenyl group, naphthyl group,
biphenyl group, anthranyl group, phenanthryl group, fluorenyl group
and pyrenyl group; and heterocyclic groups such as pyridinyl group,
pyrazinyl group, pyrimidinyl group, pyridazinyl group, triazinyl
group, indolinyl group, quinolinyl group, acridinyl group,
pyrrolidinyl group, dioxanyl group, piperidinyl group,
morpholidinyl group, piperazinyl group, triatinyl group, carbazolyl
group, furanyl group, thiophenyl group, oxazolyl group, oxadiazolyl
group, benzoxazolyl group, thiazolyl group, thiadiazolyl group,
benzothiazolyl group, triazolyl group, imidazolyl group,
benzimidazolyl group and planyl group. The above substituents may
be bonded to each other to form a six-membered aryl group or a
heterocyclic group.
[0142] A device comprising a reducing dopant in the interfacial
region between the region transporting electrons or the cathode and
the organic layer is preferable as an embodiment of the organic EL
device of the present invention. The reducing dopant is defined as
a substance which can reduce a compound having the electron
transporting property. Various compounds can be used as the
reducing dopant as long as the compounds have the specific
reductive property. For example, at least one substance selected
from the group consisting of alkali metals alkaline earth metals,
rare earth metals, oxides of alkali metals, halides of alkali
metals, oxides of alkaline earth metals, halides of alkaline earth
metals, oxides of rare earth metals, halides of rare earth metals,
organic complexes of alkali metals, organic complexes of alkaline
earth metals and organic complexes of rare earth metals can be
advantageously used.
[0143] Preferable examples of the reducing dopant include
substances having a work function of 2.9 eV or smaller, specific
examples of which include at least one alkali metal selected from
the group consisting of Na (the work function: 2.36 eV), K (the
work function: 2.28 eV), Rb (the work function: 2.16 eV) and Cs
(the work function: 1.95 eV) and at least one alkaline earth metal
selected from the group consisting of Ca (the work function: 2.9
eV), Sr (the work function: 2.0 to 2.5 eV) and Ba (the work
function: 2.52 eV). Among the above substances, at least one alkali
metal selected from the group consisting of K, Rb and Cs is more
preferable, Rb and Cs are still more preferable, and Cs is most
preferable as the reducing dopant. These alkali metals have great
reducing ability, and the luminance of the emitted light and the
life of the organic EL device can be increased by addition of a
relatively small amount of the alkali metal into the electron
injecting zone. As the reducing dopant having a work function of
2.9 eV or smaller, combinations of two or more alkali metals are
also preferable. Combinations having Cs such as the combinations of
Cs and Na, Cs and K, Cs and Rb and Cs, Na and K are more
preferable. The reducing ability can be efficiently exhibited by
the combination having Cs. The luminance of emitted light and the
life of the organic EL device can be increased by adding the
combination having Cs into the electron injecting zone.
[0144] In the present invention, an electron injecting layer which
is constituted with an insulating material or a semiconductor may
further be disposed between the cathode and the organic layer. By
disposing the electron injecting layer, leak of electric current
can be effectively prevented, and the electron injecting property
can be improved. As the insulating material, at least one metal
compound selected from the group consisting of alkali metal
chalcogenides, alkaline earth metal chalcogenides, halides of
alkali metals and halides of alkaline earth metals is preferable.
It is preferable that the electron injecting layer is constituted
with the above substance such as the alkali metal chalcogenide
since the electron injecting property can be further improved.
Preferable examples of the alkali metal chalcogenide include
Li.sub.2O, K.sub.2O, Na.sub.2S, Na.sub.2Se and Na.sub.2O.
Preferable examples of the alkaline earth metal chalcogenide
include CaC, BaO, SrO, BeC, BaS and CaSe. Preferable examples of
the halide of an alkali metal include LiP, NaPF, KF, LiCl, KCl and
NaCl. Preferable examples of the halide of an alkaline earth metal
include fluorides such as CaF.sub.2, BaF.sub.2, SrF.sub.2,
MgF.sub.2 and BeF.sub.2 and halides other than the fluorides.
[0145] Examples of the semiconductor constituting the electron
transporting layer include oxides, nitrides and oxide nitrides of
at least one metal selected from Ba, Ca, Sr, Al, Ga, In, Li, Na,
Cd, Mg, Si, Ta, Sb and Zn used singly or in combination of two or
more. It is preferable that the inorganic compound constituting the
electron transporting layer forms a fine crystalline or amorphous
insulating thin film. When the electron injecting layer is
constituted with the insulating thin film described above, a more
uniform thin film can be formed, and defects of pixels such as dark
spots can be decreased. Examples of the inorganic compound include
alkali metal chalcogenides, alkaline earth metal chalcogenides,
halides of alkali metals and halides of alkaline earth metals which
are described above.
[0146] For the cathode, a material such as a metal, an alloy, a
conductive compound or a mixture of these materials which has a
small work function (4 eV or smaller) is used as the electrode
material. Examples of the electrode material include sodium,
sodium-potassium alloys, magnesium, lithium, magnesium-silver
alloys, aluminum/aluminum oxide, Al/Li.sub.2O, Al/LiO.sub.2,
Al/LiF, aluminum-lithium alloys, indium and rare earth metals.
[0147] The cathode can be prepared by forming a thin film of the
electrode material described above in accordance with a process
such as the vapor deposition process and the sputtering
process.
[0148] When the light emitted from the light emitting layer is
obtained through the cathode, it is preferable that the cathode has
a transmittance of the emitted light greater than 10%. It is also
preferable that the sheet resistivity of the cathode is several
hundred .OMEGA./.quadrature. or smaller. The thickness of the
cathode is, in general, selected in the range of 10 nm to 1 .mu.m
and preferably in the range of 50 to 200 nm.
[0149] Defects in pixels tend to be formed in organic EL device due
to leak and short circuit since an electric field is applied to
ultra-thin films. To prevent the formation of the defects, it is
preferable that a layer of a thin film having an insulating
property is inserted between the pair of electrodes.
[0150] Examples of the material used for the insulating layer
include aluminum oxide, lithium fluoride, lithium oxide, cesium
fluoride, cesium oxide, magnesium oxide, magnesium fluoride,
calcium oxide, calcium fluoride, aluminum nitride, titanium oxide,
silicon oxide, germanium oxide, silicon nitride, boron nitride,
molybdenum oxide, ruthenium oxide and vanadium oxide. Mixtures and
laminates of the above compounds can also be used.
[0151] To prepare the organic EL device of the present invention,
for example, the anode, the light emitting layer, the hole
injecting layer where necessary and the electron injecting layer
where necessary are formed in accordance with the above process
using the above materials, and the cathode is formed in the last
step. The organic EL device may be prepared by forming the above
layers in the order reverse to that described above, i.e., the
cathode being formed in the first step and the anode in the last
step.
[0152] An embodiment of the process for preparing an organic EL
device having a construction in which an anode, a hole injecting
layer, a light emitting layer, an electron injecting layer and a
cathode are disposed successively on a substrate transmitting light
will be described in the following.
[0153] On a suitable substrate which transmits light, a thin film
made of a material for the anode is formed in accordance with the
vapor deposition process or the sputtering process so that the
thickness of the formed thin film is 1 .mu.m or smaller and
preferably in the range of 10 to 200 nm. The formed thin film is
used as the anode. Then, a hole injecting layer is formed on the
anode. The hole injecting layer can be formed in accordance with
the vacuum vapor deposition process, the spin coating process, the
casting process or the LB process as described above. The vacuum
vapor deposition process is preferable since a uniform film can be
easily obtained and the possibility of formation of pin holes is
small. When the hole injecting layer is formed in accordance with
the vacuum vapor deposition process, in general, it is preferable
that the conditions are suitably selected in the following ranges:
the temperature of the source of the deposition: 50 to 450.degree.
C.; the vacuum: 10.sup.-7 to 10.sup.-3 Torr; the rate of
deposition: 0.01 to 50 nm/second; the temperature of the substrate:
-50 to 300.degree. C. and the thickness of the film: 5 nm to 5
.mu.m; although the conditions of the vacuum vapor deposition are
different depending on the used compound (the material for the hole
injecting layer) and the crystal structure and the recombination
structure of the hole injecting layer to be formed.
[0154] Then, the light emitting layer is formed on the hole
injecting layer formed above. Using the light emitting material of
the present invention, a thin film of the organic light emitting
material can be formed in accordance with the vacuum vapor
deposition process, the sputtering process, the spin coating
process or the casting process, and the formed thin film is used as
the light emitting layer. The vacuum vapor deposition process is
preferable since a uniform film can be easily obtained and the
possibility of formation of pin holes is small. When the light
emitting layer is formed in accordance with the vacuum vapor
deposition process, in general, the conditions of the vacuum vapor
deposition process can be selected in the same ranges as those
described for the vacuum vapor deposition of the hole injecting
layer although the conditions are different depending on the used
compound.
[0155] The electron injecting layer is formed on the light emitting
layer formed above. Similarly to the hole injecting layer and the
light emitting layer, it is preferable that the electron injecting
layer is formed in accordance with the vacuum vapor deposition
process since a uniform film must be obtained. The conditions of
the vacuum vapor deposition can be selected in the same ranges as
those described for the vacuum vapor deposition of the hole
injecting layer and the light emitting layer.
[0156] In the use of the compound of the present invention,
specific procedures and conditions are different depending on
whether the compound is used for the light emitting zone or for the
hole transporting zone. When the vacuum vapor deposition process is
used, the compound of the present invention can be vapor deposited
simultaneously in combination with other materials, and when the
spin coating process is used, the compound of the present invention
can be used in combination with other materials by mixing the
materials together.
[0157] The cathode is formed on the electron injecting layer formed
above in the last step, and the organic EL device can be obtained.
The cathode is made of a metal and can be formed in accordance with
the vacuum vapor deposition process or the sputtering process. It
is preferable that the vacuum vapor deposition process is used in
order to prevent formation of damages on the lower organic layers
during the formation of the film.
[0158] In the above preparation of the organic EL device, it is
preferable that the above layers from the anode to the cathode are
formed successively while the preparation system is kept in a
vacuum after being evacuated.
[0159] The process for forming the layers in the organic EL device
of the present invention is not particularly limited. A
conventional process such as the vacuum vapor deposition process
and the spin coating process can be used. The organic thin film
layer comprising the amine-based compound of the present invention
can be formed in accordance with a conventional process such as the
vacuum vapor deposition process and the molecular beam epitaxy
process (the MBE process) or, using a solution prepared by
dissolving the compounds into a solvent, in accordance with a
coating process such as the dipping process, the spin coating
process, the casting process, the bar coating process and the roll
coating process.
[0160] The thickness of each layer in the organic thin film layer
in the organic EL device of the present invention is not
particularly limited. A thickness in the range of several
nanometers to 1 .mu.m is preferable so that defects such as pin
holes are decreased and the efficiency can be improved.
[0161] When a direct voltage is applied to the organic EL device,
emission of light can be observed under application of a voltage of
5 to 40 V in the condition that the anode is connected to a
positive electrode (+) and the cathode is connected to a negative
electrode (-). When the connection is reversed, no electric current
is observed and no light is emitted at all. When an alternating
voltage is applied to the organic EL device, the uniform light
emission is observed only in the condition that the polarity of the
anode is positive and the polarity of the cathode is negative. When
an alternating voltage is applied to the organic EL device, any
type of wave shape can be used.
EXAMPLES
[0162] The present invention will be described more specifically
with reference to examples in the following. However, the present
invention is not limited to the examples.
Synthesis Example 1
Synthesis of Compound (1)
5,8-bis[{4-(diphenylamino)phenyl}phenylamino]quinoxaline
[0163] ##STR39##
(1) Synthesis of N,N-diphenyl-N'-phenyl-p-phenylenediamine
[0164] The reaction was conducted under the stream of argon. Into a
20 ml two-necked flask, 600 mg of molecular sieves 5 A (adsorbing
zeolite composed of crystalline sodium aluminosilicate;
manufactured by Wako Pure Chemical Industries, Ltd.) was placed and
stirred under heating under a reduced pressure sufficiently. To the
above, 55 mg (the formula weight (FW): 915.70; 0.06 mmole) of
Pd.sub.2(dba).sub.3 (tris(dibenzylileneacetone) dipalladium(0)),
024 mmole (FW: 202.3; 89 .mu.l as a 2.7 M toluene solution) of
tBu.sub.3P, 807 mg (FW: 96.11; 8.4 mmole) of Na(OtBu) and 1.946 g
(FW: 324.22; 6 mmole) of 4-bromophenyldiphenylamine were added.
Then, 18.2 ml of toluene as the solvent was added, and the
resultant mixture was sufficiently stirred. To the resultant
mixture, 615 mg (FW: 93.129; 6.6 mmole) of aniline was added, and
the reaction was allowed to proceed under the refluxing condition
(about 80.degree. C.) for 6 hours. The reaction product was
filtered through Celite and sufficiently washed with ethyl acetate.
The obtained product was purified in accordance with the silica gel
column chromatography (the developing solvent: chloroform). As the
result, 1.96 g (the yield: 97%) of the object product
(N,N-diphenyl-N'-phenyl-p-phenylenediamine) was obtained (the Rf
value: about 0.8).
[0165] The obtained product was analyzed in accordance with the
field desorption mass analysis (FD-MS), and the major ion peak was
found at 336, which agreed with the calculated value. ##STR40##
(2) Synthesis of 4,7-dibromobenzothiadiazole
[0166] Into a 200 ml three-necked flask, 29.05 g (213 mmole) of
benzothiadiazole was placed and dissolved into 42.9 ml of a 47%
aqueous solution of HBr. To the obtained solution, 32.24 ml of
bromine was added dropwise at the room temperature over 20 minutes,
and then 21.3 ml of a 47% aqueous solution of HBr was added. The
resultant mixture was heated under the refluxing condition for 24
hours. After the resultant mixture was cooled to the room
temperature, the solid component was dissolved into 1100 ml of
dichloromethane. To the obtained solution, 400 ml of a saturated
aqueous solution of sodium thiosulfate was added, and the obtained
mixture was treated by extraction sufficiently in a separation
funnel. The obtained dichloromethane layer washed three times each
with 150 ml of distilled water and dried with anhydrous sodium
sulfate. The dried dichloromethane solution was concentrated to 300
ml, and the recrystallization was conducted by leaving the solution
standing at 4.degree. C. for 24 hours. The formed needle crystals
were separated by filtration, and 18.29 g (the yield; 29%) of the
object compound (4,7-dibromobenzothiadiazole) was obtained.
(3) Synthesis of 3,6-dibromo-1,2-diaminobenzene
[0167] Into a 500 ml three-necked flask equipped with a refluxing
condenser, 10.0 g (FW: 293.96; 34 mmole) of
4,7-dibromobenzothiadiazole and 400 ml of ethanol as the solvent
were placed. Under cooling with ice, 24.2 g (FW: 37.83; 640 mmole)
of sodium borohydride was added, and the resultant mixture was
sufficiently stirred for about 2 hours. When generation of a gas
(hydrogen sulfide) was not observed any more, the temperature was
adjusted at the room temperature, and the reaction mixture was left
standing for one night (about 14 hours). Then, the solvent was
completely removed under a reduced pressure, and about 400 ml of
water was added to dissolve the residue. The resultant solution was
left standing for one night, and the object product was
recrystallized (7.17 g). The obtained product was treated by
extraction with ethyl ether three times, washed with a saturated
aqueous solution of sodium chloride, dried with anhydrous sodium
sulfate and filtered. After diethyl ether was removed by
distillation, 0.88 g of the object compound
(3,6-dibromo-1,2-diaminobenzene) was obtained. The overall yield
was 82%.
(4) Synthesis of 5,8-dibromoquinoxaline
[0168] Into a 500 ml three-necked flask,
3,6-dibromo-1,2-diaminobenzene obtained in (3) described above (FW:
287.90; 24.3 mmole; 7.0 g), 300 ml of ethanol as the solvent and 50
ml of a 40% aqueous solution of glyoxal (about 44 mmole; FW: 58.04;
d=1.28) were added and the resultant mixture was stirred for 8
hours. Recrystallization was conducted 5 times using ethanol as the
solvent, and the object compound (5,8-dibromoquinoxaline) was
obtained in an approximately quantitative amount.
(5) Synthesis of Compound (1)
[0169] The reaction was conducted under the stream of argon. Into a
20 ml two-necked flask, 600 mg of molecular sieves 5 A was placed
and stirred under heating under a reduced pressure sufficiently. To
the above, 48.4 mg (FW: 915.70; 0.0528 mmole) of
Pd.sub.2(dba).sub.3, 0.212 mmole (FW: 202.3; 78.6 .mu.l as a 2.7 M
toluene solution) of tBu.sub.3P, 710 mg (FW: 96.11; 7.39 mmole) of
Na(OtBu) and 1.96 g (FW: 33.644; 5.82 mmole) of
N,N-diphenyl-N'-phenyl-p-phenylenediamine were added. Then, 16 ml
of toluene as the solvent was added, and the resultant mixture was
sufficiently stirred. To the resultant mixture, 767 mg (FW: 289.94;
2.64 mmole) of 5,8-dibromoquinoxaline was added, and the reaction
was allowed to proceed under the refluxing condition (about
120.degree. C.) for 6 hours. The reaction product was filtered
through Celite and sufficiently washed with ethyl acetate. The
obtained product was purified in accordance with the silica gel
column chromatography (the developing solvent: methylene chloride).
As the result, 1.74 g (the yield: 83%) of the object product
(Compound (1)) was obtained (the Rf value: about 0.5).
[0170] The obtained product was analyzed in accordance with FD-MS,
and the major ion peak was found at 798, which agreed with the
calculated value. The glass transition temperature as measured in
accordance with the differential scanning calorimetry (DSC) was
138.6.degree. C., and the ionization potential was 5.3 eV.
[0171] The apparatuses and the conditions of the measurements used
in FD-MS, DSC and the measurement of the ionization potential are
shown in the following.
<Measurement of FD-MS>
[0172] Apparatus: HX110 (manufactured by NIPPON DENSHI Co., Ltd.)
[0173] Conditions: [0174] voltage of acceleration: 8 kV [0175]
scanning range: m/z=50.about.1,500 [0176] species of emitter:
carbon [0177] current of emitter: 0 mA.fwdarw.2 mA/minute.fwdarw.40
mA (kept for 10 minutes) (Measurement of DSC> [0178] Apparatus:
PERKIN ELMER PYRIS 1 [0179] Conditions: [0180] (1) The first
heating: 30.degree. C..fwdarw.260.degree. C.; the rate of [0181]
temperature elevation: 10.degree. C./minute; entirely under the
atmosphere of nitrogen [0182] (2) 260.degree. C.; kept for 3
minutes [0183] (3) 260.degree. C..fwdarw.50.degree. C.; rapid
cooling at 200.degree. C./minute [0184] (4) -50.degree. C.; kept
for 10 minutes [0185] (5) The second heating: -50.degree.
C..fwdarw.260.degree. C.: the rate of [0186] temperature elevation:
10.degree. C./minute <Measurement of Ionization Potential>
[0187] Apparatus: Photoelectron spectrometer AC-1 (manufactured by
RIGAKU Co., Ltd. [0188] Conditions: powder sample; in the air
Example 1
Preparation of an Organic EL Device Using Compound (1) as the Hole
Injecting Material
[0189] A glass substrate (manufactured by GEOMATEC Company) of 25
mm.times.7 mm.times.1.1 mm thickness having an ITO transparent
electrode was cleaned by application of ultrasonic wave in
isopropyl alcohol for 5 minutes and then by exposure to ozone
generated by ultraviolet light for 30 minutes. On the surface of
the cleaned substrate at the side having the transparent electrode,
a solution obtained by dissolving Compound (1) in toluene was
applied in accordance with the spin coating process (the thickness
of the formed film 20 nm). The formed film was sufficiently dried
under a vacuum at 100.degree. C. The dried laminate was attached to
a substrate holder of a vacuum vapor deposition apparatus. To the
attached laminate, the following compound HT1 for the hole
transporting layer (the thickness of the formed layer: 20 nm), the
following compounds EM1 and D1 for the light emitting layer (the
ratio of the amounts by weight: 40:2; the thickness of the formed
layer: 40 nm), the following compound Alq for the electron
transporting layer (the thickness of the formed layer: 20 nm),
lithium fluoride (LiF) for the electron injecting layer (the
thickness of the formed layer: 10 nm) and aluminum for the cathode
were laminated successively in accordance with the vacuum vapor
deposition process, and an organic EL device was obtained.
[0190] When a voltage was applied to the obtained organic EL
device, a luminance (L) of 85 cd/m.sup.2 and a current density (J)
of 0.9 mA/cm.sup.2 were obtained at a voltage of 5 V, and excellent
luminance/voltage property, current density/voltage property and
current efficiency (L/J.times.0.1) (9.3 cd/A) were exhibited. The
chromaticity coordinates (X, Y) were (0.18, 0.35). ##STR41##
PEDOT/PSS as the hole injecting material)
[0191] An organic EL device was prepared in accordance with the
same procedures as those conducted in Example 1 except that, in the
formation of the hole transporting layer, a solution obtained by
dissolving commercial PEDOT/PSS in water was applied in accordance
with the spin coating process in place of applying the solution
prepared by dissolving Compound (1) in toluene in accordance with
the spin coating process.
[0192] When a voltage was applied to the obtained organic EL
device, a luminance (L) of 98 cd/m.sup.2 and a current density (J)
of 1.6 mA/cm.sup.2 were obtained at a voltage of 5 V, and excellent
luminance/voltage property, current density/voltage property and
current efficiency (L/J.times.0.1) (6.1 cd/A) were exhibited. The
chromaticity coordinates (X, Y) were (0.18, 0.34).
INDUSTRIAL APPLICABILITY
[0193] As described specifically in the above, the novel
amine-based compound of the present invention is suitable as the
hole injecting material and the hole transporting material for
photo-sensitive materials for electronic photography and organic EL
devices, and a thin film can be formed in accordance with the
coating process due to the excellent solubility. The organic EL
device using the amine-based compound of the present invention
exhibits excellent balance in physical properties such as a small
ionization potential, a great band gap energy, a great efficiency
of injection and a great mobility and excellent heat resistance and
efficiency of light emission. Therefore, the organic EL device is
highly practical, and suitable as devices used in vehicles to which
heat resistance exceeding 130.degree. C. is required.
* * * * *